The present invention is directed to switching mode power supplies (SMPS). More particularly, embodiments of the invention provide circuits and methods for improving the power factor of the SMPS. But it would be recognized that the invention has a much broader range of applicability.
Switching mode power supplies (SMPS) have the advantages of smaller size, higher efficiency and larger output power capability, and are widely applied in mobile phone chargers, notebook computer adapters and other fields. With the development of light-emitting diode (LED) technology as a replacement for incandescent white light bulb, SMPS is widely used as drivers for providing power to LEDs.
With the development of electronic technology, more and more electronic devices adopt LCD as display. As a kind of backlight source, light-emitting diode (LED) has many advantages, such as long lifetime, high efficiency, and no toxic material. As a result, LEDs are becoming increasingly popular as a backlight source.
As described further below, conventional LED backlight drivers have many limitations. These limitations include, for example, lack of LED current matching, inconsistency of LED brightness, and costly manufacturing process, etc.
In view of the foregoing, there is a need for improved techniques for achieving zero watts of standby energy consumption switch mode power supplies.